> char **line
You don't allocate any space with this.
char line[100][80];
would allow you to store upto 100 lines, with up to 80 chars in each line

> exit -1;
If you really want to call the function, then you need
exit ( -1 );

> while ( !feof(myfile) )
Why using feof() in a loop is a bad idea is also in the FAQ
For example, if the last line is missing a newline, then your while(c!='\n') will loop forever, trashing memory as it goes.
Furthermore, you don't reset your counter back to 0 when you go from one line to the next, nor do you end each line with a \0 to make it a proper string.

> slen[i]=j;
More unallocated memory.

Seriously, consider using fgets() to read a whole line at a time rather than trying to do it yourself one character at a time.

You should probably avoid pointers for anything except little test programs until you know how they work. The problem can be easily solved with an array to hold one line and two passes through the file: